The invention relates to a drive arrangement for a grinding, lapping or polishing tool body, said drive arrangement comprising a drive rod for the tool body.
Grinding tool bodies or, in short, grinding bodies usually are ceramically-bonded, synthetic resin-bonded, rubber-bonded or sintered abrasive substances, such as aluminum oxide, silicon carbide, boron nitride, diamond, or similar. Lapping bodies serve as lapping means carriers and preferably are made of metals, such as iron, cast iron, brass, copper, tin, lead and the like, or also of mixtures of metal powders of the aforementioned metals and synthetic resin. Lapping means, as a rule, are diamond, boron nitride, silicon carbide, aluminum oxide and the like in aqueous or oily solutions. Polishing bodies, as a rule, consist of soft materials, such as plastics, wood of different degrees of hardness, felts or cloths which take up the polishing means (diamond, boron nitride, SiC, aluminum oxide and the like).
When grinding, lapping or polishing workpieces having arched or grooved surfaces, it has been known to move an corresponding tool body over the surface of the workpiece in a manner that it is articulately coupled with a drive rod which in turn is driven by a drive system comprising a motor. At present, mainly spherical slide rod systems, cf. DE 35 18 631 A or DE 44 11 743 A are generally used, in which the tool body is provided with a spherical bore in which the drive or thrust rod engages with a spherical end. With such a drive arrangement, the tool can follow the workpiece surface in the plane of the drive rod and always rest on it in a flat state, yet it is not possible to direct the tool in circles. It has also been known to articulately connect the drive rod with a tool carrier via a hinge, with the respective lapping, polishing or grinding tool being glued to the lower side of the tool carrier. Consequently, the tool as a whole cannot fall below a certain minimum size, which again will limit the workpieces to be processed as regards the shaping of the workpiece surface which the tool will still be able to treat.
Thus, it is an object of the invention to provide a drive arrangement of the initially defined type with which the guiding movements on all sides can be transmitted to the tool body with the assistance of the drive rod so that any processing desired of the respective workpiece will be possible and by which, moreover, with a view to respectively shaped workpiece surfaces, also tool bodies of minimum size can be used.
The drive arrangement according to the invention of the initially defined type is characterised in that a substantially cylindrical groove is provided in the tool body for a substantially positive-fit, articulated connection between the tool body and the drive rod, the drive rod engaging in this groove with a rounded, flattened end thereof.
With such a design, the aforementioned object is met in an advantageous manner. The drive rod has a flattened, rounded end so that a flat, disc-shaped coupling piece is formed. The tool body itself and/or a guiding attachment fastened to its upper side, as explained later on in more detail, has a substantially cylindrical, disc-shaped recess in which the disc-shaped end of the drive rod has a positive fit. In this manner, not only reciprocating movements of the tool in the plane of the drive rod can be carried out with the assistance of the drive rod, but also movements transverse thereto, as well as, of course, also combined movements, in particular circulating movements. The tool itself may be pivoted forwards and backwards about the cylindrical axis of the disc-shaped end of the drive rod or its cylindrical groove, respectively, and thus can adapt to the surface of the workpiece during its movements.
On the whole, thus, tools with a rectangular cross-section can be used during grinding, lapping or polishing, where the longitudinal axis of the tools extends in the working direction and can be controlled. The tools may be extremely small, which is particularly important in case of highly arched workpiece surfaces. The use of small tool bodies of rectangular cross-section is also advantageous because such tool bodies are relatively simple and inexpensive to produce, in particular as ceramics bodies or as sintered bodies. Instead of the earlier, rigid articulation systems, also an at least partial movability transversely to the working direction becomes possible, making it possible to control the rotation of the tool about an axis extending perpendicular to the surface of the workpiece.
To control the tool when processing a workpiece, it is advantageous if the axes of the substantially cylindrical groove and of the rounded, flattened end of the drive rod are substantially at right angles to the working direction. Also for the exact guiding and movement transversely to the working direction it is advantageous if the axis of the rounded, flattened end of the drive rod extends in parallel to the working area of the tool body.
To provide for a an easy pivotability of the tool body in a direction transversely to the main working direction relative to the drive rod, so as to enable it to follow a respective workpiece surface profile, it is furthermore suitable if the cylindrical groove has a trapezoidal cross-section, the shorter one of the parallel sides of the trapezium being located at the bottom of the groove. For mounting the end of the drive rod in the groove of the tool body it is also advantageous if a lining is provided in the substantially cylindrical groove of the tool body, which lining preferably is made of metal or plastics, such as, e.g., of brass, aluminum, or a thermoplast or cast resin. In this way, a gentle treatment of the material of the drive rod as well as a long useful life in the region of the articulated xe2x80x9cplugxe2x80x9d connection drive rod/tool body can be achieved, by simply choosing appropriately matched working materials for lining and drive rod, or its engaging end, respectively. For transverse pivoting movements of the tool body relative to the drive rod, in turn, it is suitable if the cross-section of the lining is substantially trapezoidal.
In case of tool bodies of particular small dimensions, with particularly highly profiled workpiece surfaces, it may be suitable that the substantially cylindrical groove provided for engagement of the drive rod therein is at least partially arranged in a separate guiding or bearing attachment of the tool body so that in the tool body proper only a small depressionxe2x80x94if anyxe2x80x94need be provided. Accordingly, an advantageous embodiment with the drive arrangement according to the invention is characterized in that the tool body includes an attachment fastened thereto, which attachment preferably is made of metal or plastics, such as brass, aluminum, or a thermoplastic or cast resin, which attachment is provided with a substantially cylindrical groove or with a substantially cylindrical passage groove. In this instance, the attachment may simply be glued to the tool body, welded thereto or soldered therewith.
To avoid wear by direct contact between tool body and drive rod in case of a guiding attachment, it is furthermore also advantageous if the diameter of the substantially cylindrical passage groove of the attachment is smaller than the diameter of the substantially cylindrical groove in the tool body.
To provide for a smooth transition between the attachment and the tool body, it is also advantageous if the substantially cylindrical passage groove in the attachment has substantially the same width as the substantially cylindrical groove in the tool body.
To achieve the desired movability also in transverse direction, so as to ensure pivoting of the tool body relative to the drive rod, in case an attachment is mounted, it is also suitable if the substantially cylindrical passage groove of the attachment has a trapezoidal cross-section, the shorter one of the parallel sides of the trapezium being provided on that side which faces the tool body. In this case it is, moreover, suitable for a smooth transition to the groove in the tool body if the longer one of the parallel sides of the trapezium of the substantially cylindrical groove in the tool body and the shorter one of the parallel sides of the trapezium of the substantially cylindrical passage groove in the attachment substantially have the same lengths.
With a view to a simple installation as well as to a simple production, it is, furthermore, advantageous if the lining is connected with the attachment.
As has already been mentioned, the tool body preferably is a ceramics body or a body of sintered material in a manner known per se. For long periods of operation, the drive rod may be made of metal, yet for obtaining as light-weight an embodiment as possible, in which also an easy production is ensured, it may also be made of plastics, in particular of a fiber-reinforced plastics material.
The rounded, flattened end of the drive rod preferably is integrally formed with the remaining drive rod, yet with a view to a separate production, it may also be glued to the front side of the drive rod body later on, or cast thereto or welded thereto.